Wireless Charging Shift Ahead

Magnetic induction currently has the wireless charging market cornered and is available in Google, Samsung, and Nokia devices. Induction typically uses two magnetic coils -- a primary wire coil with an alternating electromagnetic field from within a charging base station, and a secondary coil in the device to convert power from the electromagnetic field to electrical current to charge a battery. Together, the coils create a transformer.

"If you design it right -- the right frequency and material, the quality of that coil -- you can get very efficient power transfer and design for specific distance or power," Perzow said.

Several companies have taken to inductive charging. Samsung's Galaxy S4 supports Qi, as has Google and Nokia. Perzow said the WPC has more than 40 million wireless devices on the market and has support from the semiconductor industry, Ikea, and Verizon.

The WPC offers close coil inductive technology, which draws up to five Watts and operate at 200-300 kHz. Perzow said the WPC's Qi technology can extend the charging range up to 40 mm away from the power source with 70% power efficiency.

Qi and inductive charging have been touted for having protected connections, being safe enough for medical devices, and harboring low radio frequency interference. However, inductive charging is accused of being more delicate and more inconvenient than other types of charging; users have little freedom and must line up a device precisely with a wireless charging pad.

"I think there's something to that, but the assumption is that Qi is close couple inductive, and it will be that way forever, and that's not the case," Perzow said. "It is a constantly evolving technology. Qi is not a product. You can't spec it."

I can see that wireless charging is convienent since all you have to do is place your device on a mat and it will get chaged. Has there been any information about the efficiency of this system? I expect that it is very poor. With the push to save power and create new technologies that are more efficient, I don't understand the push for wireless charging. I will continue to plug in my devices even if it only saves me a few pennies.

Wireless charging is very exciting and certainly one of the areas we will expect some innovations in the next 4-5 years. The era of bundling cables with phones is going to be over soon. I bought a laptop few months ago and there was no single CD inside it. If it crashes, you can recover online. I hope it does not get there as I have no idea what that means except maybe I am to make a startup Flash key in case.

I think much of the "push" for wireless charging has to do with limited access to charging throughout the day and the constraints that are placed on mobility by the current system. It's troubling to see how as devices become more and more complex they continue to offer little in terms of power-saving and endurance. Performance is one thing, but devices need to be operational in order to accomplish what they are intended to accomplish. That isn't being done right now and so the demand for wireless charging is on the rise.

To me, wireless charging provides the conveience with the price of low energy efficiency. The development is primarily focused on efficiency improvement. It is way better than the first generation inductive charging; yet, it can't be as good as direct contact simply by Law of Physics. Anyone can provide some measurement data of efficiency vs different method will help the community to understand. :)

I would love to see some direct comparisons as well - I found very little data on power efficiency/time in my research. Seems to me that the next hurdle to overcome in charging will be getting the efficient power transfer of inductive with resonance's ease of placement.

The challenge is the efficiency of inductive charging technology drastically falls down over distance from the charger. From user's perspective the wireless charging would add value if there are no restrictions regarding how the phone could be placed on the charger. Another requirement I could think of is that the same charger to work with phones from different manufacturers...hence I think only one among these technologies would survive in long run...and some point of time there would be a need for making a standard for this (like USB charging). Finally I would not want to change the charging station as frequently as phones...hence the technology should be forward looking, which should last for several years.

The last point from Lachman I think nicely summarizes things. There is no one single magnetic standard and there will need to be more than one power source as well. A receiving system that can easily be integrated into a device based on that device's shape and size is also very important.

Congrats on a well-researched and well-written overview article. A growing number of articles have tried to accomplish an overview of the wireless power standards development, and I find this to be the most accurate. This is speaking from 4+ years of experience as an antenna developer for wireless power devices.

There have been some very positive changes in charging with the standardization on microUSB as a common plug standard. Reading this article reminded me of the bad old days where each device needed a special cable. All that I see is a multiplicity of standards that will be going away within a couple of years. It does not make me want to commit, either as a device designer or a consumer.

@Jessica, I am actually consulting on a project right now that is using the Qi system. I would like to say that we chose it because of its technical superiority, but the cold reality is that the company owner has a co-marketing deal with that company. They probably have the upper hand right now, but if Apple or Samsung created critical mass by going another way it could be left out in the cold. The comment in the article about confusion due to competing standards is very true. The worst case is if each of those two elephants choose different standards, with maybe Sony choosing something else. That would stretch out the battle, which in the end doesn't really help anyone - much less the consumers.

My company has just finished developing a Qi based phone charger design for one of the world's largest car manufacturers.Having this built into production cars is bound to boost the Qi standard over any competing standard.

What are the costs of the wireless charging technologies? Is it practical to build a device that can support all 4 competing technologies? If such a "universal" device were made, would software updates be sufficient to accomodate subsequent device enhancements?

Until a stable standard is in place - or there is assurance of upward compatibility - consumers cannot rationally invest in the systems.

[Of course with the short SmartPhone technology life cycles, people used to buying new chargers for each new SmartPhone may be willing to expend the same funds on a new wireless charger for each generation. If so, the vision of standardized chargers for phones will have been defeated by the evolving wireless charger technologies.]

@DrQuine, good points. The shorter life cycle of smartphones changes the game. But still, someone has to pay for a charger...and there is no assurance for whatever wireless charger you invested in will last long enough to amortize your investment...

I find it especially frustrating since the wonderful initiative to standardize charger connectors so that we don't need to fill up drawers with obsolete chargers is being thwarted by the emerging multiplicity of wireless charging devices.

Based on my usage, it does two important things, it holds my phone in place and charges it without fooling around with cables when I get in my car.

Evidently it can hold up a Nexus 7 too because it uses magnets as well as a sticky surface.

It's Qi based which is fine since I'm going to use it with a Nexus 4 and Nexus 5 when I upgrade.

What does not make much sense to me are desktop pad type chargers. You're not really going to use your device while it is on the pad and as "wireless" as these chargers are, they still have a power cord.

I don't expect that these chargers are ever going to realize Tesla's dream of wireless power transmission so I don't see where low efficiency long distance (a few inches) chargers are going to be game changers for consumer electronics, a standard like Qi should do just fine (if it can support enough power).

For medical devices I can see a good case for the RF stuff but that shouldn't influence the smart phone charger market.

Bottom line, I will be using a wireless charger but I'm not giving up my standardized usb cable because it is better for many situations.

In principle, going wireless with any devices is a good thing -- for offering convenience (ease of use) and clutter-less environment.

But really, who will be the main market for this wireless charging? Home, Cars, public space (like cafes and airports)? I am struggling to find the business reasons (or key advantages) for any institutions to invest in such charging stations.

I will say the article covering two different application techniques, one for the mobile phones, tablets etc, and second for in-ear and internet of things kind of devices.

The first will not be having much acceptance in the broad market of it, only few top end customers will be ready to spend more for wireless charging, but the second application technique based on RF will become and essential entity if it proves its chargeability in real world applications.

Yes, but this does add any improvement in life, it removes the wires clutter the only way you can think it is beneficial, but Docks are already doing that. Also this requires 2A charger, where as docks will require only 1A charger, virtually doubles the power consumption.

I agree with two of the conclusions that Kinnar expressed, that there's really two markets and that the in-ear and at least some internet of things will go with RF.

As far as smartphones and tablets are concerned I would say the biggest issue is with the smartphones. Talk time, in heavy use scenarios, is way overoptimistic. Using speakerphone while browsing is very power consuming. Not only the display and the 4G but the cellular connection. In congested metropolitan areas the transmitter often has to up power to get through interference. These scenarios can drain a battery such that you can't make it through the day.

So, with the smartphone we're at the mercy of chargers during the day. The USB port, especially the 2.1A type do the job, however they are inconvenient when call is made or answered, usually disconnecting the USB connector to the phone. This is not only an inconvenience but a potential reliability problem with the phone connector.

I see charging stations becoming ubiquitous, just putting phone on a pad will be very attractive feature and certainly offices and homes can be easily equipped.

On the technical side I see a problem. In the article there is mention that the induction and resonant technologies presently have relatively low power delivery capabilities. New USB charging is specified at 2.1A, that's because the older 1A has proved inadequate. My Nokia Qi is specified to charge between 0.5 and 1.5A. Providing such technology as a feature on a car won't work. A major use for smartphones in cars is for GPS apps. The GPS apps, by default leave the display on. The current wireless charging will not even supply enough power to keep the phone from discharging.

Humavox RF talks of a range, but the main frequency mentioned is 2.4GHz-- they really should pick a different frequency than WiFi (device won't be connected to WiFi while charging? Really?) and microwave ovens (this isn't WiFi mW signal, but several thousand mW it sounds like. I am not sure I want several potential multiple watt "microwave oven" transmitters sitting on a table next to the bed, or facing me while working). Sure there are technical solutions for 2.4GHz, but the first kitten fried-- in reality or not-- by a failing Humavox 2.4GHz open top cup shaped nest "microwave oven" will severely dent their product reputation. On the up side, perhaps one could hard boil an egg in the nest while working those long hours...